x86_64: fix C abi of incomplete sse register

src/arch/x86_64/abi.zig

@@ -285,17 +285,16 @@ pub fn classifySystemV(ty: Type, zcu: *Zcu, target: std.Target, ctx: Context) [8
 
             // "If one of the classes is MEMORY, the whole argument is passed in memory"
             // "If X87UP is not preceded by X87, the whole argument is passed in memory."
-            var found_sseup = false;
+            for (result, 0..) |class, i| switch (class) {
-            for (result, 0..) |item, i| switch (item) {
                 .memory => return memory_class,
                 .x87up => if (i == 0 or result[i - 1] != .x87) return memory_class,
-                .sseup => found_sseup = true,
                 else => continue,
             };
             // "If the size of the aggregate exceeds two eightbytes and the first eight-
             // byte isn’t SSE or any other eightbyte isn’t SSEUP, the whole argument
             // is passed in memory."
-            if (ty_size > 16 and (result[0] != .sse or !found_sseup)) return memory_class;
+            if (ty_size > 16 and (result[0] != .sse or
+                std.mem.indexOfNone(Class, result[1..], &.{ .sseup, .none }) != null)) return memory_class;
 
             // "If SSEUP is not preceded by SSE or SSEUP, it is converted to SSE."
             for (&result, 0..) |*item, i| {

test/c_abi/cfuncs.c

@@ -5478,17 +5478,35 @@ f80_extra_struct c_f80_extra_struct(f80_extra_struct a) {
 #endif
 
 #ifndef ZIG_NO_F128
+__float128 zig_f128(__float128 a);
 __float128 c_f128(__float128 a) {
     assert_or_panic((double)a == 12.34);
+    assert_or_panic(zig_f128(12) == 34);
     return 56.78;
 }
 typedef struct {
     __float128 a;
 } f128_struct;
+f128_struct zig_f128_struct(f128_struct a);
 f128_struct c_f128_struct(f128_struct a) {
     assert_or_panic((double)a.a == 12.34);
+    f128_struct b = zig_f128_struct((f128_struct){12345});
+    assert_or_panic(b.a == 98765);
     return (f128_struct){56.78};
 }
+
+typedef struct {
+    __float128 a, b;
+} f128_f128_struct;
+f128_f128_struct zig_f128_f128_struct(f128_f128_struct a);
+f128_f128_struct c_f128_f128_struct(f128_f128_struct a) {
+    assert_or_panic((double)a.a == 12.34);
+    assert_or_panic((double)a.b == 87.65);
+    f128_f128_struct b = zig_f128_f128_struct((f128_f128_struct){13, 57});
+    assert_or_panic((double)b.a == 24);
+    assert_or_panic((double)b.b == 68);
+    return (f128_f128_struct){56.78, 43.21};
+}
 #endif
 
 void __attribute__((stdcall)) stdcall_scalars(char a, short b, int c, float d, double e) {

test/c_abi/main.zig

@@ -136,7 +136,7 @@ export fn zig_f64(x: f64) void {
     expect(x == 56.78) catch @panic("test failure: zig_f64");
 }
 export fn zig_longdouble(x: c_longdouble) void {
-    if (!builtin.cpu.arch.isWasm()) return; // waiting for #1481
+    if (!builtin.target.isWasm()) return; // waiting for #1481
     expect(x == 12.34) catch @panic("test failure: zig_longdouble");
 }
 
@@ -1671,7 +1671,7 @@ test "bool simd vector" {
     }
 
     {
-        if (builtin.target.cpu.arch != .wasm32) c_vector_256_bool(.{
+        if (!builtin.target.isWasm()) c_vector_256_bool(.{
             false,
             true,
             true,
@@ -2189,7 +2189,7 @@ test "bool simd vector" {
         try expect(vec[255] == false);
     }
     {
-        if (builtin.target.cpu.arch != .wasm32) c_vector_512_bool(.{
+        if (!builtin.target.isWasm()) c_vector_512_bool(.{
             true,
             true,
             true,
@@ -5614,23 +5614,64 @@ test "f80 extra struct" {
     try expect(a.b == 24);
 }
 
-extern fn c_f128(f128) f128;
+comptime {
-test "f128 bare" {
+    skip: {
-    if (!have_f128) return error.SkipZigTest;
+        if (builtin.target.isWasm()) break :skip;
 
-    const a = c_f128(12.34);
+        _ = struct {
-    try expect(@as(f64, @floatCast(a)) == 56.78);
+            export fn zig_f128(x: f128) f128 {
-}
+                expect(x == 12) catch @panic("test failure");
+                return 34;
+            }
+            extern fn c_f128(f128) f128;
+            test "f128 bare" {
+                if (!have_f128) return error.SkipZigTest;
 
-const f128_struct = extern struct {
+                const a = c_f128(12.34);
-    a: f128,
+                try expect(@as(f64, @floatCast(a)) == 56.78);
-};
+            }
-extern fn c_f128_struct(f128_struct) f128_struct;
-test "f128 struct" {
-    if (!have_f128) return error.SkipZigTest;
 
-    const a = c_f128_struct(.{ .a = 12.34 });
+            const f128_struct = extern struct {
-    try expect(@as(f64, @floatCast(a.a)) == 56.78);
+                a: f128,
+            };
+            export fn zig_f128_struct(a: f128_struct) f128_struct {
+                expect(a.a == 12345) catch @panic("test failure");
+                return .{ .a = 98765 };
+            }
+            extern fn c_f128_struct(f128_struct) f128_struct;
+            test "f128 struct" {
+                if (!have_f128) return error.SkipZigTest;
+
+                const a = c_f128_struct(.{ .a = 12.34 });
+                try expect(@as(f64, @floatCast(a.a)) == 56.78);
+
+                const b = c_f128_f128_struct(.{ .a = 12.34, .b = 87.65 });
+                try expect(@as(f64, @floatCast(b.a)) == 56.78);
+                try expect(@as(f64, @floatCast(b.b)) == 43.21);
+            }
+
+            const f128_f128_struct = extern struct {
+                a: f128,
+                b: f128,
+            };
+            export fn zig_f128_f128_struct(a: f128_f128_struct) f128_f128_struct {
+                expect(a.a == 13) catch @panic("test failure");
+                expect(a.b == 57) catch @panic("test failure");
+                return .{ .a = 24, .b = 68 };
+            }
+            extern fn c_f128_f128_struct(f128_f128_struct) f128_f128_struct;
+            test "f128 f128 struct" {
+                if (!have_f128) return error.SkipZigTest;
+
+                const a = c_f128_struct(.{ .a = 12.34 });
+                try expect(@as(f64, @floatCast(a.a)) == 56.78);
+
+                const b = c_f128_f128_struct(.{ .a = 12.34, .b = 87.65 });
+                try expect(@as(f64, @floatCast(b.a)) == 56.78);
+                try expect(@as(f64, @floatCast(b.b)) == 43.21);
+            }
+        };
+    }
 }
 
 // The stdcall attribute on C functions is ignored when compiled on non-x86